What does a solid double line in the center of the road indicate?

A solid double line in the center of the road indicates that no passing is allowed in either direction. This marking is a clear and definitive guideline for drivers, emphasizing the importance of safety on the road. Such lines are typically placed in areas where visibility is poor, where there is a high likelihood of accidents, or where the road conditions do not permit safe overtaking. The solid double line serves not only as a warning to maintain safe driving practices but also helps in ensuring that all vehicles stay within their designated lanes, thereby preventing dangerous maneuvers that could lead to collisions.

Options suggesting that passing is allowed either on one or both sides misrepresent the purpose of the double lines, while the mention of a bike lane is unrelated to the function of road markings concerning vehicle passing regulations.